The present invention is directed to methods of making granular food products and the resultant products.
Agglomeration has been used in the food industry for a long time to produce agglomerates with improved dispersability from fine powders. The known use of water as agglomerating agent generally is limited to the agglomeration of water soluble particles which after having been wetted stick together forming liquid bridges. During drying the liquid bridges are transformed into stable solid bridges. Furthermore, processing of hygroscopic food powders using water as spraying agent often results in defluidization due to overwetting.
U.S. Pat. No. 4,557,938 to Sander et al. discloses a process for improving the dispersion of a vegetable gum in water. The process comprises dry blending a food grade particulate carrier and vegetable gum particles, fluidizing the mixture with an air stream, intermittently spraying water onto the fluidized bed so that the surfaces of the particles become wet and tacky, resulting in the particles sticking to each other. Subsequently, the process comprises air drying for the time intervals during which no water is sprayed, resulting in the particles becoming bound to each other. The spraying and drying intervals being continued until agglomerated particles are formed.
The present invention provides a mechanically stable, free flowing granular food product having an improved wettability and hot dispersability so that the granular food product may be dispersed while being simply poured into hot water, not provided in the prior art. The present invention also provides a process for the production of a mechanically stable, free flowing granular food product having an improved wettability and hot dispersability so that it may be dispersed while being simply poured into hot water.
The present invention relates to a granular food product that includes a filler and a high melting fat present in combination in amounts sufficient to impart body and flavor components to the granular food product, with the filler being present in an amount that is greater than that of the high melting fat; and a binding agent present in an amount sufficient to bind the filler and a high melting fat to form the granular food product. Advantageously, the granular food mixture has a mean particle diameter of about 600 xcexcm to about 1200 xcexcm, with less than about 3% by volume of particles having a diameter smaller than 200 xcexcm and a moisture content of about 1% to about 6% by weight of the product.
Preferably, less than about 10% by volume of the particles have a diameter that is smaller than about 300 xcexcm and less than 10% by volume of the particles have a diameter that is greater than 1900 xcexcm, and the filler is present in an amount that is about 9 to 45 times as great as the amount of the high melting fat. Also, the granular food product preferably has a span in diameter distribution from about 1 to about 2, a moisture content of between about 3 and 4.5% by weight of the product, and a critical bulk weight that is greater than about 4.3 mm.
The filler is advantageously present in an amount of about 78% to about 92% by weight of the product, and is selected from the group consisting of flour, starch, spices, milk powder, sugar, salt, bouillon masses, extracts, flavorings, fruit powders, and mixtures thereof. The filler is preferably selected from the group consisting of wheat flour, corn flour, soya flour, potato starch, wheat starch, corn starch, spice mixes, vegetable extract, meat extract, yeast extract, spice extract, and mixtures thereof. The binding agent is advantageously present in an amount of about 2% to about 8% by weight of the product, and is selected from the group consisting of a vegetable gum, gum arabic, guar gum, gum carrageenan, and mixtures thereof. The high melting fat is advantageously present in an amount of about 2% to about 10% by weight of the product and is selected from the group consisting of palm fat, beef fat, chicken fat, and mixtures thereof. Preferably, the high melting fat has a melting point temperature of about 45xc2x0 C. to about 60xc2x0 C.
The invention also relates to a process for making a granular food product comprising the steps of preparing a premix of at least one filler and at least one high melting fat, wherein the filler is present in an amount that is greater than the amount of high melting fat; forming the premix into a granules or agglomerates having a mean particle diameter of about 600 xcexcm to about 1200 xcexcm, with less than about 3% by volume of particles having a diameter smaller than 200 xcexcm; and drying the granules or agglomerates to form a granular food product.
Preferably, the amount of filler is between about 9 and 45 times as much as that of the fat and a binding agent is added to the premix in an amount sufficient to bind the filler and fat in the agglomerates or granules. Typically, the premix is prepared by mixing powdered constituents including from about 2% to about 10% of a high melting fat and from about 78% to about 92% of a filler by percentage weight of the granular food product. The step of forming the premix into granules or agglomerates generally comprises atomizing an aqueous solution containing about 10% to about 30% of binding agent onto a fluidized bed of the premix until a total amount of about 2% to about 8% by weight of granulated food product is atomized and incorporated into the premix. The aqueous solution of binding agent may be atomized into droplets having a mean diameter of about 40 xcexcm to about 120 xcexcm through a binary nozzle under a pressure of from 0.5 to 1.0 bar. The premix may be fluidized by injecting a stream of gas through at least one inlet and into the bottom of a fluidized bed agglomeration tower that contains the premix, wherein the gas has a temperature of about 80xc2x0 C. to about 120xc2x0 C. Preferably, the gas is air and the aqueous solution is atomized for about 5 min to about 25 min before the granules are dried for about 1 min to about 10 min. Also, the temperature of the premix during the formation of the granules or agglomerates is about 50xc2x0 C. to 65xc2x0 C.
If desired, the granules may be cooled in the tower with an ascending current of air having a temperature of about 10xc2x0 C. to about 30xc2x0 C. Also, the step of drying the granules generally is conducted to dry the granules to a residual moisture content of from about 1% to about 6% by weight, and preferably to about 3% to about 4.5% by weight of the granular food product.
The invention also relates to a process for making a granular food product by preparing a premix of at least one filler, at least one high melting fat, and a binding agent, wherein the filler is present in an amount that is greater than the amount of high melting fat and the binding agent is present in an amount sufficient to bind the filler and the fat, atomizing an aqueous solution comprising an amount of the binding agent onto a fluidized bed of the premix so as to form the premix into granules or agglomerates having a mean particle diameter of about 600 xcexcm to about 1200 xcexcm, with less than about 3% by volume of particles having a diameter smaller than 200 xcexcm, and drying the granules or agglomerates to form a free-flowing granular food product that is mechanically stable and easily dispersible in hot water. All of the above process embodiments apply to this aspect of the invention, as well. The invention also relates to granular food products prepared by this process.
As used herein, the expression xe2x80x9cmechanically stablexe2x80x9d means resistant to disintegration during filling and stocking into a pack, particularly into an individual pack.
As used herein, the mean diameter is defined as a 50% limit (D50) in particle distribution whereby 50% by volume of the particles have a diameter below the 50% limit and 50% by volume of the particles have a diameter above the 50% limit.
The outstanding properties of the present granular food product, in so far as it is free flowing and easily dispersible in hot water, may be checked and defined by means of particle size analysis and wettability tests as described herein.
In addition to allowing the production of a granular food product having these outstanding properties, the present process makes it possible to produce the granular food product from hygroscopic powdered food materials. Hygroscopic powdered food materials include, but are not limited to, bouillon masses, extracts, flavorings, fruit powders, or inert powdered food materials including, but not limited to, flours, starches or spice mixes. Preferably, the hygroscopic powdered food materials do not get tacky while being wetted and, after having been agglomerated with water, disintegrate and recover their original powdered form after drying.
Preferably, the granular food product has less than about 10% by volume of the particles have a diameter smaller than about 300 xcexcm and less than about 10% by volume of the particles have a diameter greater than about 1900 xcexcm. More preferably, the granular food product particles have a span in diameter distribution of from about 1 to about 2. As used herein, the term xe2x80x9cspanxe2x80x9d is defined as the broadness or width in particle distribution between a 10% limit (D10) and a 90% limit (D90) divided by the mean particle diameter (D50), whereby 10% by volume of the particles have a diameter below the 10% limit and 10% by volume of the particles have a diameter above the 90% limit.
As used herein, unless otherwise defined, the expression xe2x80x9chigh melting fatxe2x80x9d means a fat having a melting temperature above ambient temperature. Preferably, the high melting fat has a melting temperature of from about 45xc2x0 C. to about 60xc2x0 C. The high melting fat may be a vegetable or animal fat, including, but not limited to, palm fat, beef fat, chicken fat, or mixtures thereof.
Typically, the binding agent may be a sugar, polysaccharide, or a mixture thereof. Preferably, the binding agent is a vegetable gum including, but not limited to, gum arabic, guar gum, gum carrageenan, or mixtures thereof.
The filler may be any powdered food material. In particular, the filler is a powdered food material comprising swelling particles, powdered food material or both with a mean particle diameter of which is smaller than about 300 xcexcm. Preferably, the fillers are selected from the group consisting of flour, starch, spices, milk powder, sugar, salt, bouillon masses, an extract, flavorings, fruit powders, and mixtures thereof. More preferably, the filler is selected from the group consisting of wheat flour, corn flour, soya flour, potato starch, wheat starch, corn starch, spice mixes, vegetable extract, meat extract, yeast extract, spice extract, and mixtures thereof.
The process of the present invention for the production of a granular food product comprises the steps of preparing a premix of powdered constituents, forming the premix into granules or agglomerates, and drying the granules.
Preparing the premix comprises mixing powdered constituents of the high melting fat and a filler, preferably where the filler is present in an amount that is much greater than that of the fat. Advantageously, from about 2% to about 10% of high melting fat and from about 78% to about 92% of filler by percentage weight of the granular food product are mixed together. Preferably, the high melting fat is heated to a temperature above its melting point in order to be in liquid form. Mixing of the premix may be carried out by means of any suitable traditional powder mixer, including, but not limited to, a horizontal mixer with plow-shaped heads arranged on a horizontal shaft or a ribbon mixer.
Forming the premix into granules or agglomerates typically comprises atomizing an aqueous solution containing about 10% to about 30% of binding agent onto a fluidized bed of the premix until a total amount of from about 2% to about 8% of binding agent, by weight of granular food product, has been atomized and incorporated therein.
Forming the premix into granules or agglomerates by atomizing a solution of binding agent onto a fluidized bed of the premix may be carried out in any batch fluidized bed agglomeration equipment of the food industry. The equipment generally consists of a tower. In the lower part of the tower, the premix is fluidized by a stream of gas injected through one or more gas inlets provided for at or near the bottom of the tower. In a middle part of the tower, the solution of binding agent may be atomized into the fluidized bed through an adequate nozzle including, but not limited to, a binary nozzle. In an upper part of the tower, the gas used for fluidizing and/or heating or cooling the product is filtered before escaping through one or more exhaust pipes provided for at or near the top of the tower.
It has been found that the present process allows the powdered constituents of the premix to be formed into granules or agglomerates having both a relatively large mean diameter and a relatively narrow span in diameter distribution, by making the particles of powdered constituents tacky rather than wet before the particles enter into collision with each other so that they actually adhere and remain adhered to each other after collision.
In a preferred embodiment, an agglomerate may be formed by atomizing droplets of an aqueous solution of binding agent in such a way that they arrive in a nearly dry state, namely in a very thick and sticky state onto the particles so that the particles immediately get very tacky. Thus, if the premix is formed into granules or agglomerates by atomizing an aqueous solution containing less than about 10% of binding agent, there is a risk that the premix of powdered constituents gets too wet and not tacky enough. Alternatively, if the premix is formed into granules or agglomerates by atomizing an aqueous solution containing more than about 30% of binding agent, there is a risk of lack of efficiency due to too high a viscosity of the solution.
The present process preferably comprises fluidizing the premix with an ascending current of air having a relatively high temperature of from about 80xc2x0 C. to about 120xc2x0 C. More preferably, the present process comprises atomizing the aqueous solution of binding agent in form of droplets having a relatively large mean diameter of from about 40 xcexcm to about 120 xcexcm. One method to obtain this size is by atomizing the aqueous solution of binding agent through a binary nozzle under a relatively low pressure of from about 0.5 about 1 bar, and preferably at a pressure of about 0.7 to 0.9 bar.
Preferably, the temperature of the product during agglomeration is from about 50xc2x0 C. to about 65xc2x0 C. If the temperature of the product during agglomeration is less than about 50xc2x0 C., there is a risk that the premix of powdered constituents gets too wet and not tacky enough. If the temperature of the product during agglomeration is greater than about 65xc2x0 C., there is a risk that the premix of powdered constituents dries before it is agglomerated.
The agglomeration process may be carried out in a relatively short time. Preferably, the aqueous solution is atomized for about 5 min to about 25 min and the granules are dried for about 1 min to 10 min. The granules may then be cooled with an ascending current of air having a temperature of from about 10xc2x0 C. to about 30xc2x0 C.
Drying may be carried out using any conventional methods. One of ordinary skill in the art with little or no experimentation can easily determine the appropriate drying methods for a particular granular food product. Typically, the granules are dried to a residual moisture content of from about 1% to about 6%, preferably to a residual moisture content of from about 3% to about 4.5% by weight of the granular food product.
Embodiments of the granular food product and of the process for producing the granular food product according to the present invention are illustrated in the following non-limiting examples in which the percentages are by weight of the granular food product unless indicated to the contrary.